The present application claims priority under 35 U.S.C. xc2xa7119 of German Patent Application No. 298 11 048.2 filed Jun. 19, 1998, German Patent Application No. 198 16 673.7 filed Apr. 15, 1998, and German Patent Application No. 198 48 284.1 filed Oct. 20, 1998, the disclosures of which are expressly incorporated by reference herein in their entireties.
The invention relates to a press device and process for treating a material web, in particular a paper or a cardboard web.
The present invention provides a compact press device which is as inexpensive as possible and which has a simple design. Further, the present invention provides a press device requiring low operating costs, which ensures an optimal web guidance and which also ensures, as much as possible, less rewetting of the material web and increased overall efficiency in treating a material web.
The present invention may be related to a calender roll system and provides increased efficiency and lower costs associated with treating a material web. The press device of the present invention includes two separate shoe presses positioned next to each other. The press device of the present invention further includes a transfer suction roll which is disposed between the two shoe presses. The material web, together with a felt, are continuously guided by the transfer suction roll, which is at least partially provided with suction, in a continuous manner. The material web is transported through at least one of the two shoe presses.
According to one embodiment of the invention, the distance between the nips of the two shoe presses may be relatively short. Further, it is possible to guide the web over a completely closed or a continuous, partially suctioned path. This may be particularly advantageous by requiring a low degree of rewetting of the material web, a lower decree of treating the web on both sides, and increased efficiency. The operating costs may be kept relatively low, particularly with respect to the felts, the drive, the vacuum production, the maintenance, and the like. The press device of the present invention is further distinguished by its reasonable manufacturing costs. For example, the vacuum requirement is considerably reduced because the large press suction roll required in the prior art, which included a thick jacket, is no longer necessary.
On the whole, the present invention results in the utilization of considerably lower drive power. Further, because a closed or continuous web guidance system is possible, the corresponding press section is particularly well suited for paper webs which have a low basis weight or which use high machine speeds. The number of felts is reduced to a minimum, which results in lower operating costs. The operating costs are further reduced by the lower vacuum requirement for suction devices as well as the lower drive power. The present invention also decreases initial investment costs, in that fewer guide rolls, regulators, clamps, suction devices, doctors, troughs, and the like are required. Further, a simpler, lever-free, and compact seating is also possible such that three cantilever carriers are sufficient.
According to the present invention, only one base felt is necessary so that there is more space available for certain subassemblies, such as the pulper. Also, the overall maintenance cost is considerably lower. The elimination of press roll mechanics tends to further minimize the initial investment costs. The lack of blade wear, maintenance and replacement decreases the operating costs as well as increases the availability of the machines to treat the material web. The lubricant spray tube may be eliminated. Further, the paper tension after the press section is decreased.
It is generally true that, if the number of the rolls and roll types used is reduced to a minimum, the number of rolls that have to be kept on hand is also correspondingly low, which in turn decreases the investment costs. Because the pick-up rolls, transfer rolls, and transfer suction rolls used in the invention may often be structurally identical, the number of rolls that must be kept on hand is reduced. Thus, the investment costs and maintenance costs can also be kept low.
The lengthy roll service lives also turn out to be advantageous. Thus, the use of a press suction roll is eliminated and hard covers are used practically exclusively. Moreover, because crowns are no longer required, an endless combination of line force regions with varying forces are possible. There is, for example, no line force dependency between the two nips.
Due to the compact embodiment, the space required for the relevant press section is minimal. For example, in a width of 5.5 m, approximately 10 m or less in the longitudinal direction of the press device is sufficient. The low spatial volume results in low investment costs both for the machine and the relevant building space that must be acquired or dedicated for this process.
Moreover, there is good accessibility. In a respective press jacket replacement, oil cannot get into the felt. In addition, the felt does not interfere with the jacket replacement. The relevant shoe press unit can be easily withdrawn for service work. To this end, for example, it is possible for there to be a travel-out carriage on a cantilever carrier. Removing the felt is not necessary for a respective withdrawal of the shoe press unit. The felt and roll replacement is embodied as extremely simple on the whole. One cantilevering per felt is sufficient. There is good accessibility to the rolls for a roll replacement via a crane. The form width can be varied with no trouble. Fundamentally, it is also possible for there to be a closed guidance (draw) of the web from the wire section to the end of the drying section.
Advantageously, the felt that is guided together with the material web over the transfer suction roll, may be routed through both shoe presses.
According to the present invention, each of the two shoe presses may be double felted.
According to another embodiment of the present invention, the press device as a whole may have a closed or continuous web guidance, which produces an increased efficiency and practically eliminates tears in the press device. A manual design is no longer required, which results in a correspondingly higher operational reliability and a high degree of machine availability. Due to the lack of open draws, it is practically impossible for paper stretching or web tearing to occur. In particular, the web does not have to be pulled away from smooth roll surfaces. Between the presses, the paper is no longer subjected to any fluctuations in tension. A corresponding tensile force coupling by way of a respective felt produces the desired synchronism. An ideal web guidance is always assured for both brown and white papers. This results in short rewetting segments and a good web securing between the presses.
In yet another embodiment of the present invention, the press device further includes a web holding box positioned after the transfer suction roll. More particularly, the web holding box may be placed between the suction roll and the subsequent shoe press.
According to one aspect of the invention, a pick-up felt is routed through at least the first shoe press which the material web encounters in the web travel direction.
Moreover, it is possible for one of the two shoe presses to be formed by a shoe press unit disposed on the bottom and a counter roll disposed on top. In one embodiment of the press device, both of the shoe presses are respectively formed by a shoe press unit disposed on the bottom and a counter roll disposed on top. The material web, together with a bottom felt which is routed through both the shoe presses, may be guided over the transfer suction roll.
For example, one of the two shoe presses can also be constituted by a shoe press unit disposed on top and a counter roll disposed on the bottom. In a suitable embodiment of the press device according to the invention, both of the shoe presses are respectively constituted by a shoe press unit disposed on top and a counter roll disposed on the bottom. In this instance, the material web is preferably guided over the transfer suction roll together with a top felt that is routed through both shoe presses.
In yet another aspect of the present invention, at least one shoe press unit is formed by a shoe press roll.
In an embodiment form that is particularly suited for liner with a white cover (xe2x80x9cwhite topxe2x80x9d), the shoe press that comes last in the web travel direction is single felted and the relevant counter roll may be touched or in contact with the material web.
The present invention is directed to a press device for treating a material web. The press device includes a first shoe press and a second shoe press. The first and the second shoe press are successively arranged in a web run direction. A transfer suction roll is positioned between the first shoe press and the second shoe press and is adapted to at least partially suction the material web and to guide the material web in a closed draw through at least one of the first and the second shoe presses.
According to another feature of the present invention, a transport felt is adapted for use with the transfer suction roll to guide the material web in the closed draw through the at least one of the first and the second shoe presses.
According to still another feature of the present invention, the material web may be composed of a paper web.
In accordance with still another feature of the present invention, the material web may be composed a cardboard web.
In a further feature of the present invention, a transport felt may be guided over the transfer suction roll and may be guided through the first shoe press and the second shoe press.
According to a still further feature of the present invention, the first and the second shoe presses are composed of double felted shoe presses.
In accordance with another feature of the present invention, the material web may be guided through the press device in a closed draw.
According to still another feature of the present invention, a web holding box may be located after the transfer suction roll relative to a web run direction and before the second shoe press.
In a further feature of the present invention, a felt may be guided through a first one of the first and the second shoe presses relative to a web run direction. The felt may be a pick-up felt.
In accordance with a still further feature of the present invention, at least one of the first and the second shoe presses may be composed of a shoe press unit and a counter roll. The shoe press unit may be positioned beneath the counter roll.
Further, each of the first and the second shoe presses may be composed of a shoe press unit and a counter roll. The shoe press units may be positioned beneath the counter rolls. The transfer suction roll may be positioned between the counter rolls and above a plane that extends through nips formed by the first and the second shoe presses. Further, the counter rolls may have a smooth surface. Further still, the counter rolls may have at least one of a grooved and blind bored surface. Still further, the shoe press units may be composed of shoe press rolls. The shoe press units may include press jackets, and the press jackets may have at least one of a grooved and blind bored surface. The counter rolls may be internally supported.
According to another feature of the present invention, a bottom felt may be guided through both of the first and the second shoe presses. The bottom felt may be adapted to guide the material web over the transfer suction roll.
In accordance with a further feature of the present invention, at least one of the first and the second shoe presses may be composed of a shoe press unit and a counter roll. The shoe press unit may be positioned on top of the counter roll. Further, each of the first and second shoe presses may be composed of a shoe press unit and a counter roll. The shoe press unit may be positioned on top of the counter roll. Further still, the transfer suction roll may be positioned between the counter rolls and below a plane that extends through nips formed by the first and the second shoe presses.
According to a still further feature of the present invention, a bottom felt may be guided through the first and the second shoe presses, and the bottom felt may be adapted to guide the material web over the transfer suction roll.
In accordance with yet another feature of the present invention, at least one of the first and the second shoe presses may be oriented obliquely to vertical at an angle up to approximately 30xc2x0.
According to stil another feature of the present invention, at least one of the first and the second shoe presses may be oriented vertically.
According to another feature of the present invention, a transport felt may be adapted to guide the material web through the first and the second shoe presses and around the transfer suction roll.
According to still another feature of the present invention, the transfer suction roll may include a plurality of suction zones successively arranged in a web run direction.
In accordance with a further feature of the present invention, a heating device may be positioned in a region of the transfer suction roll to act on a surface of the material web not in contact with the transfer suction roll.
The present invention may also be directed to a process for treating a material web in an apparatus that includes a first shoe press and a second shoe press, which are positioned adjacent each other, and a transfer suction roll positioned between the first shoe press and the second shoe press. The process may include at least partially suctioning the material web with the transfer suction roll, and guiding the material web in a closed draw through at least one of the first and the second shoe presses.
In accordance with another feature of the present invention, the apparatus may further include a transport felt, and the process further includes guiding the material web in the closed draw on the transport belt and through the at least one of the first and second shoe presses via the transport belt. Moreover, the process may include guiding the material web in the closed draw on the transport belt and through the first and the second shoe presses.
In a further feature of the present invention, the apparatus may further include a pick-up felt, and the process may further include pressing the material web between the pick-up felt and transport felt in a first one of the first and second shoe presses relative to a web run direction.
The process of the present invention may further include picking up the material web from a wire sieve with the transport belt.
According to still another feature of the present invention, the process may further include heating the web as it is guided over the transfer suction roll.
In accordance with a still further feature of the present invention, the transfer suction roll may include a plurality of suction zones successively arranged in the web run direction, and the process may further include suctioning the material web with at least one of the plurality of suction zones.
In accordance with yet another feature of the present invention, the process may further include guiding two press felts through the at least one of the first and the second shoe press, and pressing the material web between the two press felts in the at least one of the first and the second shoe presses.
Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure and the accompanying drawing.